Richard George is correct the 5998 may sound better for high impedance phones. If you have a lower impedance phone get some 6336s for the
It will still work it would be better with the switch but it will still work and drive lower impedance phones better.
I have wanted to try my W3000ANV on the OTL. I'll take a look at a set of the 6336 tubes to try. I think I have the 3DG4/6F8G/5998 combo running now. I have to look when I get home.
What is the impedance of the W3000ANV ???
Usually the SX-1980 with the -20db muting enabled. I sold my one push-pull amp (MP-301 Mk2), but that was before I owned the cans.
I have a few 6AS7 around. I'll try those and look for some 6080 to try.
I found the W3000ANVs to be noisy with the OTL. They are not a good match.
After moving 3.75 miles NE to another residence, even the 2359glenn OTL Silver Hawk decided to move from its prior position inside the rack. Now front and center.
Regarding my current audio adventure using ZERO Autoformers, it's over. I yanked 'em this evening and moved them over to the Tea room to await return shipping. The ZEROs are ideal for my 6 Ohm KEF Coda 9's but less than ideal for the 50 Ohm power hungry, inefficient and demanding HiFiMAN HE-6.
I really like what Glenn did for Clayton SF - made custom pigtails with integrated resistors.... a really clean fabrication!